NAME

Net::DNS::ToolKit::RR::PTR - Resource Record Handler

SYNOPSIS

  DO NOT use Net::DNS::ToolKit::RR::PTR
  DO NOT require Net::DNS::ToolKit::RR::PTR

  Net::DNS::ToolKit::RR::PTR is autoloaded by 
  class Net::DNS::ToolKit::RR and its methods
  are instantiated in a 'special' manner.

  use Net::DNS::ToolKit::RR;
  ($get,$put,$parse) = new Net::DNS::ToolKit::RR;

  ($newoff,$name,$type,$class,$ttl,$rdlength,
        $ptrdname) = $get->PTR(\$buffer,$offset);

  Note: the $get->PTR method is normally called
  via:  @stuff = $get->next(\$buffer,$offset);

  ($newoff,@dnptrs)=$put->PTR(\$buffer,$offset,\@dnptrs,
	$name,$type,$class,$ttl,$ptrdname);

  $name,$TYPE,$CLASS,$TTL,$rdlength,$IPaddr) 
    = $parse->XYZ($name,$type,$class,$ttl,$rdlength,
        $ptrdname);

DESCRIPTION

Net::DNS::ToolKit::RR:PTR appends an PTR resource record to a DNS packet under construction, recovers an PTR resource record from a packet being decoded, and converts the numeric/binary portions of the resource record to human readable form.

  Description from RFC1035.txt

  3.2.1. Format

  All RRs have the same top level format shown below:

                                    1  1  1  1  1  1
      0  1  2  3  4  5  6  7  8  9  0  1  2  3  4  5
    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
    |                      NAME                     |
    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
    |                      TYPE                     |
    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
    |                     CLASS                     |
    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
    |                      TTL                      |
    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
    |                   RDLENGTH                    |
    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--|
    |                     RDATA                     |
    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+

  NAME	an owner name, i.e., the name of the node to which this
	resource record pertains.

  TYPE	two octets containing one of the RR TYPE codes.

  CLASS	two octets containing one of the RR CLASS codes.

  TTL	a 32 bit signed integer that specifies the time interval
	that the resource record may be cached before the source
	of the information should again be consulted.  Zero
	values are interpreted to mean that the RR can only be
	used for the transaction in progress, and should not be
	cached.  For example, SOA records are always distributed
	with a zero TTL to prohibit caching.  Zero values can
	also be used for extremely volatile data.

  RDLENGTH an unsigned 16 bit integer that specifies the length
	in octets of the RDATA field.

  RDATA	a variable length string of octets that describes the
	resource.  The format of this information varies
	according to the TYPE and CLASS of the resource record.

    3.3.12. PTR RDATA format

    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
    /                   PTRDNAME                    /
    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+

    where:

    PTRDNAME A <domain-name> which points to some location 
	in the domain name space.

PTR records cause no additional section processing. These RRs are used in special domains to point to some other location in the domain space. These records are simple data, and don't imply any special processing similar to that performed by CNAME, which identifies aliases. See the description of the IN-ADDR.ARPA domain for an example.

• @stuff = $get->PTR(\$buffer,$offset);

  Get the contents of the resource record.
  
  USE: @stuff = $get->next(\$buffer,$offset);
  
  where: @stuff = (
  $newoff $name,$type,$class,$ttl,$rdlength,
  $ptrdname );

  All except the last item, $ptrdname, is provided by the class loader, Net::DNS::ToolKit::RR. The code in this method knows how to retrieve $ptrdname.

    input:        pointer to buffer,
                  offset into buffer
    returns:      offset to next resource,
                  @common RR elements,
  		PTR Domain Name

• ($newoff,@dnptrs)=$put->PTR(\$buffer,$offset,\@dnptrs, $name,$type,$class,$ttl,$ptrdname);

  Append an PTR record to $buffer.

    where @common = (
  	$name,$type,$class,$ttl);

  The method will insert the $rdlength and $ptrdname, then pass through the updated pointer to the array of compressed names

  The class loader, Net::DNS::ToolKit::RR, inserts the @common elements and returns updated @dnptrs. This module knows how to insert its RDATA and calculate the $rdlength.

    input:        pointer to buffer,
                  offset (normally end of buffer), 
                  pointer to compressed name array,
                  @common RR elements,
  		PTR Domain Name
    output:       offset to next RR,
                  new compressed name pointer array,
             or   empty list () on error.

• (@COMMON,$PTRDNAME) = $parse->PTR(@common,$ptrdname);

  Converts binary/numeric field data into human readable form. The common RR elements are supplied by the class loader, Net::DNS::ToolKit::RR. For PTR RR's, this returns the $ptrdname terminated with '.'

  input:	PTR Domain Name
  returns:	PTR Domain Name.

DEPENDENCIES

Net::DNS::ToolKit
Net::DNS::Codes
Net::DNS::ToolKit::RR::NS

EXPORT

none

AUTHOR

Michael Robinton <michael@bizsystems.com>

COPYRIGHT

Copyright 2003, Michael Robinton <michael@bizsystems.com>

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

See also:

Net::DNS::Codes(3), Net::DNS::ToolKit(3)